Dual chamber mixing syringe and method for use

ABSTRACT

A mixing syringe and method for using the mixing syringe are provided. The mixing syringe comprises a housing having a first compartment for containing a first component, an outer plunger having a second compartment for containing a second component, and an inner plunger. Prior to use, a seal separates the first and second components. To prepare the mixture, the seal is pierced and the two components are mixed. The mixing syringe and its method of use are particularly suited to applications in which at least one of the mixture components is a relatively highly viscous material.

PRIORITY CLAIM

The present application claims priority to U.S. Provisional ApplicationNo. 60/514,045, filed on Oct. 24, 2003, which is hereby incorporatedherein by reference.

FIELD OF THE INVENTION

The present invention relates devices for mixing two components to forma mixture. More specifically, the present invention relates to a syringehaving two chambers for receiving two constituents that are to be mixed,and the method for using such a device.

BACKGROUND OF THE INVENTION

Many drugs are stored in separate components that are mixed before use.Typically, the separate components include a powder and a liquiddiluent. By storing the components separately, shelf life of the drug isincreased.

With many of these drugs, the separate components are stored in asyringe and mixed within the syringe prior to use. The components arestored in separate chambers in the syringe prior to use. To prepare themedicine, the separate components are combined into a single chamber inthe syringe, shaken and then the solution is ready for injection into apatient.

Although such a system works well for mixtures that are highly soluble,they are ineffective for less soluble mixtures. Specifically, the knownsystems combine the two components of a medicine into a single chamberand the mixture is then shaken to dissolve the components into solution.However, certain components cannot be adequately mixed by simplycombining and shaking the two elements together.

SUMMARY OF THE INVENTION

In light of the foregoing shortcomings of the prior art and in order toprovide an improved syringe, the present invention provides an improvedsyringe that is operable to mix separate components to prepare amedicinal fluid for use. The syringe is particularly suited to mix drugshaving low viscosity and/or low solubility.

More specifically, the present invention provides a mixing syringehaving a housing that includes a first fluid chamber for containing afirst component of a medicine. Within the housing is a first plungerhaving a second fluid chamber for containing a second component of themedicine. Within the first plunger is a second plunger. A seal separatesthe first and second components, to prevent the components from becomingmixed during storage. Preferably, the syringe also includes a needle anda valve for preventing the discharge of the medicine through the needlewhile the components are being mixed.

Another aspect of the invention provides a method for mixing a medicineusing a dual chamber syringe having a housing, a first plunger and asecond plunger. A first component of the medicine is stored in a fluidchamber within the housing and a second component of the medicine isstored in a second chamber within the housing. Preferably, the secondchamber is within the first plunger. A seal separates the two componentsduring storage.

The method includes opening the separation seal to permit fluid flowbetween the first and second chambers to allow the two components tomix. The first plunger is displaced to drive the first components of themedicine into the second chamber. The second plunger is then displacedto drive the first and second components into the first chamber. Thefirst and second plungers are then repeatedly displaced in analternating fashion to drive the combined first and second componentsback and forth between the first and second chambers to mix the twocomponents. After the components are mixed, either the first or secondplunger is displaced forwardly to eject the mixture from the syringe.

Another aspect of the invention provides a syringe having two fluidchambers containing two medicinal components and a seal separating thecomponents from one another. A needle is attached to the syringehousing, and a valve controls the flow of fluid from the housing throughthe needle.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing summary and the following detailed description of thepreferred embodiments of the present invention will be best understoodwhen read in conjunction with the appended drawings, in which:

FIG. 1 is a dual chamber mixing syringe manifesting aspects of thepresent invention, shown in the syringe prior to use;

FIG. 2 is the syringe of FIG. 1, illustrating the syringe after a sealhas been pierced;

FIG. 3 is the syringe of FIG. 1, illustrating the syringe after a firstmedicinal component has been transferred from a first fluid chamber to asecond fluid chamber;

FIG. 4 is the syringe of FIG. 1, illustrating the syringe after themedicinal fluid has been transferred from the second fluid chamber backinto the first fluid chamber;

FIG. 5 is the syringe of FIG. 4, illustrating the syringe with anapplicator attached;

FIG. 6 is the syringe of FIG. 5, illustrating the syringe after themedicine is expelled from the syringe;

FIG. 7 is a side view partially in section of an alternative mixingsyringe, illustrating the syringe prior to use;

FIG. 8 is a side view partially in section of the syringe of FIG. 7,illustrating the syringe after a valve has been opened;

FIG. 9 is a cross sectional view of the syringe of FIG. 7, illustratingthe syringe after medicine has been expelled from the syringe;

FIG. 10 is an enlarged fragmentary perspective view of a valve elementof the syringe;

FIG. 11 is an enlarged fragmentary cross-sectional view of the valveelement of FIG. 10;

FIG. 12 is a fragmentary side view partially in section of a secondalternative mixing syringe;

FIG. 13 is a fragmentary side view partially in section of the syringeof FIG. 12 with a needle cover removed;

FIG. 14 is a fragmentary perspective view of the forward end of thesyringe illustrated in FIG. 12;

FIG. 15 is a fragmentary perspective view partially in section of theforward end of the syringe illustrated in FIG. 14;

FIG. 16 is a perspective view of a third alternative mixing syringe;

FIG. 17 is a fragmentary partially exploded view of the syringeillustrated in FIG. 16;

FIG. 18 is a fragmentary perspective view partially in section of thesyringe illustrated in FIG. 17;

FIG. 19 is a perspective view of the syringe of FIG. 16, showing thesyringe with a valve in an opened position;

FIG. 20 is a fragmentary perspective view partially in section of thesyringe of FIG. 19;

FIG. 21 is a side view partially in section of the syringe of FIG. 19;

FIG. 22 is a side cross-sectional view of a fourth alternative mixingsyringe;

FIG. 23 is a side cross-sectional view of the syringe illustrated inFIG. 22, illustrating the syringe after a seal has been pierced; and

FIG. 24 is an enlarged fragmentary view of a portion of a plunger of thesyringe illustrated in FIG. 22.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the figures generally, and to FIGS. 1-6 specifically,wherein like elements are numbered alike, a mixing syringe is designatedgenerally 10. The syringe 10 is a dual chamber syringe that houses twocomponents of a medicine and maintains the elements separately duringstorage. Prior to use, the elements are combined and mixed togetherwithin the syringe. Particularly, preferably the two components aremixed by repeatedly transferring the two components back and forthbetween two fluid chambers 24, 37 within the syringe 10. After themedicine is thoroughly mixed, the medicine is expelled from the syringe.

More specifically, the syringe 10 includes a hollow housing 20, a hollowouter plunger 30 disposed within the housing and an inner plunger 50disposed within the outer plunger. A seal 25 on the end of the housingseals the housing closed. Preferably, a first medicinal component isstored within the housing 20 and a second component is stored within theouter plunger 30.

To mix the components, the first component is transferred into the outerplunger 30 by pushing the outer plunger forwardly. The two componentsare then transferred into the housing 20 by pushing the inner plunger 50forwardly. To thoroughly mix the components together, the components arerepeatedly transferred back and forth between the housing 20 and thechamber within the outer plunger 30 by alternatively pushing forward theouter plunger and the inner plunger. After the two components arethoroughly mixed, the seal 25 is removed and the medicine is expelledfrom the syringe by pushing forward one of the plungers.

Referring now to FIG. 1, the details of the syringe will now bedescribed in greater detail. The outer housing 20 is configured similarto a typical syringe barrel. The rearward end of the housing isgenerally opened for receiving the outer barrel 30. The forward end ofthe housing is generally closed having a reduced diameter openingforming a discharge opening. Preferably, the forward end and thedischarge opening forms a nozzle 22, such as a Luer lock fitting. Theseal 25 is configured to cooperate with the nozzle to seal the forwardopening of the housing 20. More specifically, preferably the sealcomprises external threads that cooperate with the Luer lock threads sothat the seal threadedly engages the housing.

Adjacent the rearward open end of the housing are a pair of opposingflanges 27 that project outwardly from the housing. The flanges formfinger gripping elements for the operator to grasp during use. Theinterior of the housing forms a fluid chamber 24 and preferably thefirst medicinal component is stored in the fluid chamber in the housingas discussed further below.

The outer plunger 30 is configured to slide within the interior of thehousing 20, similar to a plunger in a standard syringe. However, theouter plunger is hollow to receive the second medicinal component andthe inner plunger 50 as discussed further below.

The outer plunger 30 comprises an elongated hollow plunger rod 35 and apiston 32 attached to the forward end of the plunger rod. The rearwardend of the outer plunger 30 is generally opened for receiving the innerplunger 50. The forward end of outer plunger is generally closed, havinga reduced diameter opening forming a fluid path for transferring themedicinal components between the housing and the interior of the outerplunger, as discussed further below.

Referring still to FIG. 1, the forward end of the outer plunger 30preferably forms a tip that cooperates with the piston 32 to connect thepiston to the outer plunger. Specifically, preferably the tip of theouter plunger rod 35 forms a barbed connector 45. In addition,preferably the outer plunger rod includes a piercing element 41 forpiercing the seal that separates the two medicinal components. Thepiercing element may be formed in a variety of configurations. Forinstance, the piercing element may be a sharpened tip formed on theforward end of the tip of the outer plunger. However, preferably thepiercing element 41 is a needle bonded to the tip of the outer plunger.

The piston 32 is an elastomeric element that forms a fluid-tight sealwith the interior wall of the housing. The piston 32 has a bore forminga fluid path through the piston. A pierceable wall or septum 34 isformed in the piston to seal the fluid path through the piston. When theouter plunger is pushed further into the piston, the sharpened end ofthe needle 41 pierces the septum 34 and extends into a recess formed inthe forward end of the piston 32. The recess in the forward end of thepiston opens to the interior of the housing 20 so that when the needle41 projects into the forward recess, the needle is in fluidcommunication with the interior of the housing, allowing medication toflow between the housing and the interior of the outer plunger.

At least one, and preferably two recesses 33 in piston 32 matinglyengage the barb 45 of the outer plunger 30. Specifically, the piston 32preferably includes two radially relieved portions or recesses 33 a, 33b that mate with the head of the barb 45. The first radial recess 33 ais formed in the piston 32 toward the rearward end of the piston, andthe second radial recess 33 b is formed in the interior of the pistonadjacent to the septum 34. As shown in FIG. 1, prior to use, the plungerrod 35 is connected to the piston 32 so that the head of the barb 45engages the first radial recess 33 a in the piston. In this position,the needle 41 does not pierce the septum 34 of the piston 32. To preparethe device 10 for use, the medical professional displaces the outerplunger 30 forwardly relative to the piston 32, thereby displacing thehead of the barb 45 into engagement with the second radial recess 33 b,as shown in FIG. 2. At the same time, the needle 41 pierces the septum34, so that the needle 41 is in fluid communication with the medicinalcomponent in the housing 20.

The connection between the outer plunger 30 and the piston 32 ispreferably a one-way engagement. In other words, when the piston 32 ismounted on the outer plunger 30, the plunger can be displaced forwardlyrelative to the piston, but the outer plunger can not be displacedrearwardly relative to the piston. In this way, the outer plunger cannotbe readily removed from the piston 32, such that the outer plunger issubstantially permanently attached to the piston.

The one-way connection is provided by a one-way sliding engagementbetween the barb 45 and the radial recesses 33 a, 33 b in piston 32. Thebarb 45 has forward-facing tapered edges that mate with tapered faces inthe radial recesses 33 a, 33 b. The barb 45 also has sharp or squareforward facing edges that mate with square edges in the radial recesses33 a, 33 b. The tapered edges on the barb 45 and radial recesses 33 a,33 b are tapered in the forward direction, permitting forward slidingdisplacement of the outer plunger 30 relative to the piston 32. Thesquare edges on the barb 45 and in the recesses 33 a, 33 b operate asstops that impede forward displacement of the outer plunger 30 relativeto the piston 32.

Adjacent the rearward open end of the outer plunger 30 are a pair ofopposing flanges 39 that project outwardly from the outer plunger. Theflanges form finger gripping elements for the operator to grasp duringuse. The interior of the outer plunger 30 is hollow, forming a fluidchamber 37 and preferably the second medicinal components is stored inthe fluid chamber in the outer plunger as discussed further below.

The inner plunger 30 comprises an elongated hollow plunger rod 54 and apiston 52 attached to the forward end of the plunger rod. The innerplunger 50 is configured to slide within the interior chamber 37 of theouter plunger 30. More specifically, the piston 52 forms a fluid-tightseal with the interior wall of the fluid chamber 37 in the outer plunger30. In this way, the inner plunger is operable to slide within the outerplunger to expel fluid from within the outer plunger.

Method Of Use

Referring now to FIGS. 1-6, the operation of the syringe 10 will now bedescribed in detail. In FIG. 1 the syringe is shown prior to use. Morespecifically, the configuration in FIG. 1 is referred to as an“as-shipped” configuration, and is the configuration in which thesyringe is stored prior to use. In this “as-shipped” configuration, thefirst medicinal component is preferably in the fluid chamber 24 in thehousing and the second medicinal component is preferably in the fluidchamber 37 in the outer barrel.

The two components of the medicine may both be fluids, however, onecomponents can be a liquid diluent and the other element may be apowder. In the present instance, preferably, a liquid component ispreferably stored in the housing 20 and a powder component is preferablystored in the outer plunger 30. In the “as-shipped” configuration inFIG. 1, the powder and liquid components are maintained separately bythe septum 34 in piston 32, that has not been pierced by the needle 41.

Referring now to FIG. 2, to prepare the syringe for use, the outerplunger 30 is displaced forwardly. The operator displaces the outerplunger by grasping the finger grips 27 on the housing and the fingergrips 39 on the outer plunger and squeezing the two together to push theouter barrel forward. Since fluid is disposed in the housing, and thefluid is incompressible, the fluid maintains the piston in place whilethe plunger rod 35 is displaced forwardly. In this way, the barbedconnector 45 on the end of the piston rod 35 is displaced forwardlydisengaging the first recess 33 a in the piston 32 and engaging thesecond recess 33 b. As the plunger rod 35 is displaced forwardlyrelative to the piston 32, the needle 41 pierces the septum 34. Bypiercing the septum 34, the fluid path through the piston 32 and the tipof the plunger rod 35 is opened, so that the fluid chamber 24 in thehousing and the fluid chamber in the outer plunger are in fluidcommunication.

Referring now to FIG. 3, after the septum 34 is pierced as shown in FIG.2, the two medicinal components are combined together. Morespecifically, preferably, the fluid component in the housing 20 istransferred to the fluid chamber 37 within the outer plunger 30. Thefluid is transferred by continuing to push on the outer barrel bygrasping the finger grips 27, 39 on the housing and the outer plungerand squeezing them together. Since the seal 25 seals the forward end ofthe housing, when the outer plunger 30 moves forward the fluid has nowhere to go but into the fluid chamber within the outer plunger. Morespecifically, pushing the outer plunger forwardly causes the fluid toflow out of the fluid chamber 24 in the housing through the piston 32,the needle 41 and the tip of the plunger rod 35, and into the fluidchamber in the outer plunger 30. As the fluid enters the outer plunger30, the fluid pressure created by the fluid transfer displaces innerplunger 50 rearwardly to provide a larger area in the outer plunger toaccommodate the fluid. By pushing the outer plunger 30 forwardly untilthe piston 32 abuts the forward end of the housing, substantially all ofthe fluid is transferred out of the housing fluid chamber 24 and intothe outer plunger fluid chamber 37.

As described above, the transfer of the fluid from the housing 20 to theouter plunger 30 is aided by the fact that the forward end of thehousing is sealed by seal 25. Accordingly, it is desirable to provide aconnection between the seal 25 and the nozzle 22 that can withstand thehigh fluid pressures created during the transfer, and maintain the fluidseal. Although a frictional engagement between the nozzle and the sealmay be sufficient in certain instances, preferably the nozzle and sealhave a stronger mechanical engagement such as a threaded engagement.

Referring to FIGS. 3 and 4, once the components of the medicine arecombined in a single chamber, the components are to be mixed. In certainapplications, the components can be sufficiently mixed by simply shakingthe syringe after the components are combined. However, with certain lowsolubility mixtures and/or high viscosity fluids, more rigorous mixingis necessary to properly prepare the medicine for use.

Accordingly, preferably the mixture is transferred back and forthbetween the outer plunger 30 and the housing 20. The mixture istransferred to the housing 20 by displacing the inner plunger 50forwardly, as shown in FIG. 4. More specifically, the operator graspsthe finger grips 39 on the outer barrel and a push pad on the end of theinner plunger 50 and squeezes them together. This action displaces theinner plunger 50 forwardly within the fluid chamber 37 in the outerplunger 30, thereby displacing the mixture forwardly through the fluidpath in the tip of the plunger rod 35, the needle 41 and the piston 32.The fluid pressure created from the transfer of the mixture into thehousing 20 drives the outer plunger 30 rearwardly relative to thehousing, so that the fluid chamber 24 in the housing expands toaccommodate the volume of the mixture along with any air that was in theouter plunger.

To continue mixing the mixture, the mixture is transferred back into theouter plunger 30 by pushing the outer plunger forward, as describedabove. Again, the mixture can be further mixed by transferring themixture back into the housing by pushing forward the inner rod. In thisway, the mixture can be thoroughly mixed by repeatedly transferring themixture between the chamber 24 in the housing and the chamber 37 in theouter plunger. The repeated transfer is accomplished by alternativelypushing forward the outer plunger 30 and the inner plunger 50. Thenumber of times that the mixture needs to be transferred to mix themedicine sufficiently depends upon the characteristics of the twocomponents. In some instances it may only require a few transfers of thecomponents. In other instances it may require upwards of 100 or moretransfers to mix the components sufficiently.

Referring now to FIG. 5, once the mixture is thoroughly mixed, the seal25 is removed from the housing and a dispenser tip is connected to thenozzle 22. The mixture can be expelled from the syringe directly fromthe outer plunger 30 by displacing the inner plunger 50 forwardly.However, preferably, before the seal 25 is removed, the mixture istransferred into the chamber in the housing.

The dispenser tip 60 can be any of a variety of tips depending upon theprocedure employed for using the medicine. As shown in FIG. 5, thedispenser tip can be a tapered nozzle shaped tip. In other applicationsthe dispenser tip may be a needle for injecting the mixture into apatient.

Referring now to FIG. 6, after the dispenser tip is attached, themixture is expelled by pushing the outer plunger 30 forwardly within thehousing 20. The outer plunger 30 is pushed forward until the piston 32abuts the forward wall of the housing to thereby expel all of themixture from the syringe 10.

Referring now to FIGS. 7-11 an alternative embodiment of a syringe isdesignated generally 110. The syringe 110 in this alternative embodimentoperates substantially similar to the syringe 10 described above.Referring to the previously described syringe, the syringe includes aseal to separate the two components during storage. In the previouslydescribed syringe 10 the seal is provided by a pierceable wall or septum34. However, various alternative sealing elements can be utilized toseparate the two components during storage. The alternative embodimentshown in FIGS. 7-11 describes a seal that is different from the seal 34in the first embodiment. All of the remaining elements in thealternative embodiment are preferably substantially similar to theelements illustrated in FIG. 1-6 and described above.

The syringe 110 includes a hollow housing 120 having a nozzle 122, afluid chamber 124, a seal 125 and finger grips 127. Each of theseelements is substantially similar to the housing 20, nozzle 22, fluidchamber 24, seal 25 and finger grips described previously for the firstembodiment, except as otherwise discussed below. In addition, thesyringe 110 includes an inner plunger 150 that has an elongated plungerrod 154 and a piston 152, that are substantially similar to the plunger50, plunger rod 54 and piston 52 described previously for the firstembodiment, and forming a fluid-tight seal with the interior of theouter plunger 130.

The outer plunger 130 includes a plunger rod 135 and a piston 132 thatforms a fluid-tight seal with the inner wall of the fluid chamber 124 inthe housing 120. The outer plunger 130 is hollow, forming a fluidchamber 137 for receiving a component of the medicine.

The piston 132 is attached to the plunger rod 135 using a barbedconnector 145 similar to the syringe 10 described previously. Morespecifically, as in the previous embodiment, preferably the piston 132includes a pair of recess 133 that are configured to cooperate with thebarbed connector in a manner similar to the connection described abovein detail in connection with the first syringe 10. Accordingly, thedescription of the details of the recesses 133 and the barbed connector145 and the details of operation of these elements are similar to thosedescribed above in connection with the recess 33 a, 33 b and the barbedconnector 45 of the first syringe 10.

The piston 132 and the plunger rod 135 are configured differently fromthe previously described piston 32 and plunger rod 35 to provide adifferent seal between the housing fluid chamber 124 and the outerplunger fluid chamber 137. Specifically, the end of the plunger rod 135forms a tip 147 having an circumferential rib that seats with the borein the piston 132 to form a fluid-tight seal. A side port 146 in the endof the plunger rod 135 spaced rearwardly from the tip 147 provides afluid passageway around the tip.

Referring to FIGS. 7, 10-11, in the “as-shipped” configuration, the barb145 is in the first recess 133. In this position, the tip 147 isdisposed within the piston 132 and the interior bore of the piston formsa fluid-tight seal with the tip to seal the fluid path through thepiston and the end of the plunger rod 135. Referring to FIGS. 8, 10-11,by pushing forward on the outer plunger, the barb is displaced intoengagement with the second recess 133 and the tip is displaced forwardlyfrom the piston 132 so that the side port 146 is no longer sealed by thepiston. In this way, the piston 132 and the end of the plunger rod 135operate similarly to a sliding valve. In the open position illustratedin FIG. 8, a substantially unobstructed fluid path is provided betweenthe housing fluid chamber 124 and the outer plunger fluid chamber 137.The fluid flows from the housing 120 through the side port 146 throughthe conduit in the barbed connector 135 and into the outer plunger.

Referring now to FIG. 9, in order to limit dead space in the syringe110, preferably the forward end of the fluid chamber 124 in the housingis configured to cooperate with the end of the outer plunger 130. Morespecifically, as can be seen in FIGS. 8 and 9, the tip 147 of the outerplunger extends forwardly from the piston 132. Accordingly, preferablythe housing fluid chamber 124 has a constricted forward portion thatclosely corresponds to the diameter of the tip 147. In this way, thereis less room for residual medicine to remain in the housing after thepiston engages the forward end of the housing 120.

Referring now to FIGS. 12-15 a second alternative syringe is designatedgenerally 210. The syringe 210 illustrated in FIGS. 12-15 is similar tothe syringe 110 illustrated in FIG. 7-11 and described above. However,the syringe 210 includes a needle 260 attached to the housing, and aseal or valve that is operable to prevent the discharge of medicinethrough the needle while the components are mixed within the syringe ina manner similar to the method described previously.

The syringe 210 includes a housing 220 having a fluid chamber 224. Anouter plunger 230 having a piston 232, plunger rod 235, fluid chamber237, barbed connector 245, side port 246 and tip 247 that aresubstantially similar to the piston 132, plunger rod 135, fluid chamber137, barbed connector 145, side port 146 and tip 147 described above inconnection with the previous embodiment 110.

The syringe further includes an inner plunger having an elongated pistonrod and piston seal that are substantially similar to the piston rod andpiston of the previous embodiments 52, 54,152,154. In addition, as inprevious embodiments, the inner piston forms a fluid-tight seal with thefluid chamber in the outer plunger 230.

Referring to FIGS. 14-15, the details of the tip of the housing will bedescribed in greater detail. The tip 222 of the housing 220 includes apair of molded cut-outs so that two radially displaceable arms 223 areformed in the wall of the tip of the housing. The arms are molded sothat they are biased outwardly so that the arms project outward from theexternal surface of the tip 222.

A flexible conduit 228 is disposed within the tip 222 of the housing.The flexible conduit 228 is formed of an elastomeric material so thatthe walls of the conduit are resiliently radially deformable.Accordingly, when the arms 223 are displaced radially inwardly the endsof the arms pinch the flexible conduit 228 sealing off the fluid pathwaythrough the flexible conduit.

As shown in FIGS. 12-13, the forward end of the tip forms a reduceddiameter bore. The needle is fixedly attached to the tip within thereduced diameter bore.

Referring now to FIG. 12, the syringe includes a needle shield 265 thatserves two functions: the shield encloses the needle to preventinadvertent contact with the needle prior to use; and the shieldsqueezes the arms 223 inwardly to seal off the fluid pathway through theflexible conduit 228. More specifically, the needle shield has an openrearward end having an internal bore configured similarly to theexterior surface of the tip of the housing 222. In this way, when theneedle shield 265 is attached to the tip 222 of the housing, the needleshield compresses the tip, displacing the arms 223 inwardly so that thearms pinch closed the flexible conduit. The seal provided by the pinchedconduit is sufficient to withstand the fluid pressure generated duringthe transfer of fluid between the fluid chamber 224 in the forward endof the housing and the fluid chamber 237 in the outer plunger 237 duringthe mixing process, which is described previously in connection with thefirst syringe 10.

Referring to FIG. 13, after the medicine is mixed in the syringe 210,the needle shield 265 is removed. The arms 223 resiliently rebound anddisplace radially outwardly thereby unclamping the flexible conduit 228.In this way, removing the needle shield opens the fluid path through theflexible conduit so that the medicine in the housing can be expelledthrough the needle to provide an injection.

Referring now to FIGS. 16-21 a third alternative syringe 310 isillustrated. The syringe 310 illustrated in FIGS. 12-15 is similar tothe syringe 210 illustrated in FIG. 12-15 and described above. However,the syringe 310 includes a alternate valve or seal sealing the housingto prevent the discharge of medicine through the needle while thecomponents are mixed within the syringe in a manner similar to themethod described previously.

The syringe 310 includes a housing 320 having a fluid chamber 324. Anouter plunger 330 having a piston 332, plunger rod 335, fluid chamber337, barbed connector 345, side port 346 and tip 347 that aresubstantially similar to the piston 132, plunger rod 135, fluid chamber137, barbed connector 145, side port 146 and tip 147 described above inconnection with previous embodiment 110.

The syringe 310 further includes an inner plunger 350 having anelongated piston rod 354 and piston seal 352 that are substantiallysimilar to the piston rod and piston of the previous embodiments 52,54,152,154. In addition, as in previous embodiments, the inner pistonforms a fluid-tight seal with the fluid chamber in the outer plunger330.

Referring to FIGS. 16-18, the details of the tip of the housing 220 willbe described in greater detail. The tip 322 of the housing is configuredto accommodate a rotary valve 370 that controls the flow of fluid fromthe housing 320 through the needle 360. Specifically, referring to FIGS.16 and 18, the tip 322 includes a side bore for receiving the valve 370,and a fluid passage way that cooperates with the valve as discussedfurther below.

The valve 370 is a cylindrical element having a fluid passageway 372.When the fluid passageway 372 is aligned with the fluid passagewaythrough the tip (see FIG. 20), the valve is open and fluid can flowthrough the needle. When the fluid passageway 372 through the valve 370is mis-aligned with the fluid passageway in the tip 322 (see FIG. 18),the valve is closed and is prevents the flow of fluid through theneedle. Accordingly, the valve 370 is operable between an openedposition and a closed position to control the flow of fluid through theneedle. As in the previous embodiment, the valve 370 is configured towithstand the fluid pressure created during the transfer of thecomponents in the mixing process. As shown in FIGS. 17 and 19, the valveincludes an external lever for rotating the valve between the opened andclosed positions.

Configured in this way, the syringe 310 is operable to mix twocomponents as described above while the needle is attached, while alsopreventing the medicine from being discharged from the syringe duringthe mixing process. After the medicine is mixed, the valve is rotatedinto the opened position and the medicine can be expelled by pushing theouter plunger forwardly.

Referring now to FIGS. 22-24 a third alternative embodiment of a syringeis designated generally 410. The syringe 410 in this alternativeembodiment operates substantially similar to the syringe 10 describedabove. Referring to the previously described syringe, the syringeincludes a seal to separate the two components during storage. In thepreviously described syringe 10 the seal is provided by a pierceablewall or septum 34. The outer plunger 30 has a piercing element 41 in theform of a needle that is operable to pierce the seal 34. In the presentembodiment 410, the outer plunger 430 includes a piercing element 441 inthe form of a spear that is operable to pierce the seal. The remainingelements in the alternative embodiment are preferably substantiallysimilar to the elements illustrated in FIGS. 1-6 and described above.

The syringe 410 includes a hollow housing 420 having a nozzle 422, afluid chamber 424, and a seal 425. Each of these elements is similar tothe housing 20, nozzle 22, fluid chamber 24, and seal 25 describedpreviously for the first embodiment, except as otherwise discussedbelow. In addition, the syringe 410 includes an inner plunger 450 thathas an elongated plunger rod 454 and a piston 452, that aresubstantially similar to the plunger 50, plunger rod 54 and piston 52described previously for the first embodiment, and forming a fluid-tightseal with the interior of the outer plunger 430.

The outer plunger 430 includes a plunger rod 435 and a piston 432 thatforms a fluid-tight seal with the inner wall of the fluid chamber 424 inthe housing 420. The outer plunger 430 is hollow, forming a fluidchamber 437 for receiving a component of the medicine.

The piston 432 is attached to the plunger rod 435 using a barbedconnector 445 similar to the syringe 10 described previously. Morespecifically, as in the previous embodiment, preferably the piston 432includes a pair of recess 433 that are configured to cooperate with thebarbed connector in a manner similar to the connection described abovein detail in connection with the first syringe 10. Accordingly, thedescription of the details of the recesses 433 and the barbed connector445 and the details of operation of these elements are similar to thosedescribed above in connection with the recess 33 a, 33 b and the barbedconnector 45 of the first syringe 10.

The piston 432 and the plunger rod 435 are configured differently fromthe previously described piston 32 and plunger rod 35 to provide adifferent piercing mechanism. Specifically, the end of the plunger rod435 forms a conical tip 447 forming a point or spear. In the presentembodiment, the tip 447 is integrally formed with the outer plunger rod435 as a single molded part. A side port 446 in the end of the plungerrod 435 spaced rearwardly from the tip 447 provides a fluid passagewayaround the tip.

Referring to FIG. 22, in the “as-shipped” configuration, the barb 445 isin the first recess 433. In this position, the tip 447 is disposedwithin the piston 432 and the interior bore of the piston forms afluid-tight seal with the tip to seal the fluid path through the pistonand the end of the plunger rod 435. Referring to FIG. 23, by pushingforward on the outer plunger, the barb is displaced into engagement withthe second recess 433, the tip 447 pierces the seal 434 and the tip 447is displaced forwardly from the piston 432 so that the side port 446 isno longer sealed by the piston. In the open position illustrated in FIG.23, a substantially unobstructed fluid path is provided between thehousing fluid chamber 424 and the outer plunger fluid chamber 437. Thefluid flows from the housing 420 through the side port 446 through theconduit in the barbed connector 435 and into the outer plunger.

Referring now to FIG. 23, in order to limit dead space in the syringe410, preferably the forward end of the fluid chamber 424 in the housingis configured to cooperate with the end of the outer plunger 430. Morespecifically, as can be seen in FIG. 23, the tip 447 of the outerplunger extends forwardly from the piston 432. Accordingly, preferablythe housing fluid chamber 424 has a constricted forward portion thatclosely corresponds to the diameter of the tip 447. In this way, thereis less room for residual medicine to remain in the housing after thepiston engages the forward end of the housing 420.

It will be recognized by those skilled in the art that changes ormodifications may be made to the above-described embodiments withoutdeparting from the broad inventive concepts of the invention. Forinstance, the device has been described as operable to mix together twocomponents of a medicinal fluid. The components may be a fluid and a drypowder. Alternatively, the two components may both be fluid. In certainapplications, one or more of the materials may be a relatively highlyviscous material. Furthermore, the present mixing syringe and the methodof use are not limited to applications in which medicinal fluids aremixed. For instance, the syringe and its use are applicable to a widerange of applications for mixing two-part mixtures. For example, thesyringe and method of use can be used mix two-part epoxy. It shouldtherefore be understood that this invention is not limited to theparticular embodiments described herein, but is intended to include allchanges and modifications that are within the scope and spirit of theinvention as set forth in the claims.

1. A method for mixing a mixture with a syringe, comprising the stepsof: providing a mixing syringe having a housing containing a firstconstituent of the mixture, a first plunger slideably displaceablewithin the housing having a mixing chamber containing a secondconstituent of the mixture, and a second plunger slideably displaceablewithin the first plunger, wherein a separation seal separates the firstconstituent from the second constituent prior to use; opening theseparation seal to permit flow between the housing and the mixingchamber to allow the mixing of the first and second constituents;driving the first plunger forwardly to displace the first constituentinto the mixing chamber; driving the second plunger forwardly todisplace the first and second constituents from the mixing chamber intothe housing; repeatedly alternatingly displacing the first and secondplungers forwardly to repeatedly displace the first and secondconstituents between the mixing chamber and the housing to mix the firstand second constituents; and displacing one of the first and secondplungers forwardly to eject the mixed first and second constituents fromthe mixing syringe.
 2. The method of claim 1 wherein the mixing syringecomprises a discharge seal sealing a discharge opening of the syringe,wherein the method comprises the step of unsealing the discharge sealafter mixing the first and second constituents.
 3. The method of claim 2wherein the seal comprises a valve, and the step of unsealing the sealcomprises opening the valve.
 4. The method of claim 2 wherein the sealis a removable seal and the step of unsealing the seal comprisesremoving the seal.
 5. The method of claim 2 wherein the mixing syringecomprises a needle attached to the housing during the mixing of thefirst and second constituents.
 6. The method of claim 1 wherein themixing syringe comprises a needle attached to the housing during themixing of the first and second constituents.
 7. The method of claim 1wherein the separation seal comprises a pierceable seal and the step ofopening the separation seal comprises the step of piercing theseparation seal.
 8. The method of claim 1 wherein the separation sealcomprises a valve and the step of opening the separation seal comprisesthe step of opening the valve.
 9. The method of claim 8 wherein the stepof opening the valve comprises the step of displacing one of the firstplunger and the second plunger.
 10. The method of claim 1 wherein thestep of opening the separation seal comprises the step of displacing oneof the first plunger and the second plunger.
 11. A mixing syringe formixing a mixture, comprising: a housing having a first fluid chambercontaining a first component of the mixture; a first plunger slideablydisplaceable within the housing having a second fluid chamber containinga second component of the mixture wherein the first plunger is operableto eject the first component from the first chamber by displacing thefirst plunger forwardly; a seal separating the first component from thesecond component prior to use; a second plunger slideably displaceablewithin the first plunger wherein the second plunger is operable to expelthe second component from the second chamber by displacing the secondplunger forwardly, whereby upon unsealing the separation seal,alternatively repeatedly displacing the first and second plungersoperates to displace the first and second components between the firstand second fluid chambers to mix the first and second components; aneedle attached to the housing; and a valve operable to prevent flow offluid through the needle during the mixing of the first and secondcomponents. 12-42. (canceled)
 43. A method for mixing a mixture with asyringe, comprising the steps of: providing a mixing syringe having ahousing configured to receive a first constituent of the mixture, afirst plunger slideably displaceable within the housing having a mixingchamber configured to receive a second constituent of the mixture, and asecond plunger slideably displaceable within the first plunger,selecting the first constituent such that the first constituent is afluid having a relatively high viscosity; filling the housing with thefirst constituent; filling the first plunger with the secondconstituent; sealing the first constituent from the second constituent;opening the seal between the first and second constituents to permitflow between the housing and the mixing chamber to allow the mixing ofthe first and second constituents; driving the first plunger forwardlyto displace the first constituent into the mixing chamber; driving thesecond plunger forwardly to displace the first and second constituentsfrom the mixing chamber into the housing; repeatedly alternatinglydisplacing the first and second plungers forwardly to repeatedlydisplace the first and second constituents between the mixing chamberand the housing to mix the first and second constituents; and displacingone of the first and second plungers forwardly to eject the mixed firstand second constituents from the mixing syringe.
 44. The method of claim43 comprising the step of selecting the second constituent such that thesecond constituent is a fluid having a relatively high viscosity. 45.The method of claim 43 wherein the mixing syringe comprises a dischargeseal sealing a discharge opening of the syringe, wherein the methodcomprises the step of unsealing the discharge seal after mixing thefirst and second constituents.
 46. The method of claim 1 wherein thestep of opening the seal comprises the step of piercing a pierceableseal.
 47. The method of claim 46 wherein the step of opening the sealcomprises the step of displacing one of the first plunger and the secondplunger.
 48. The method of claim 1 wherein the step of repeatedlydisplacing the first and second plungers comprises displacing the firstplunger forwardly to expel the first and second constituents from thehousing into the mixing chamber.
 49. The method of claim 48 wherein thestep of displacing the first plunger forwardly to expel the first andsecond constituents is operable to displace the second plunger withinthe first plunger.
 50. The method of claim 43 wherein the step ofrepeatedly displacing the first and second plungers comprises displacingthe first plunger forwardly to expel the first and second constituentsfrom the housing into the mixing chamber.
 51. The method of claim 50wherein the step of displacing the first plunger forwardly to expel thefirst and second constituents is operable to displace the second plungerwithin the first plunger.